Evaluation of Using Nutrient Matrix Values for Three Multi Enzymes on Growth Performance, Water Intake, Litter Moisture, Jejunal Viscosity, and Some Gastrointestinal Tract Traits of Broiler Chickens Fed Wheat-Soybean Meal-Based Diets

Background: Cereal gains form the largest portion of the poultry industry. The most important cereal in this industry is corn grain, but the presence of some issues, including the change and fluctuation of corn prices accompanied by a shortage of corn gain in some conditions in our country, have forced poultry farmers to explore different substitutional grains, such as wheat. Compared with corn, wheat grain has some advantages over corn, including improving the pellet quality and having more crude protein along with higher lysine, methionine, arginine, phenylalanine, tryptophan, threonine, and valine. However, two drawbacks to wheat grain have limited its usage in poultry diets in some conditions. On the one hand, wheat has lower metabolizable energy than corn. On the other hand, non-starch polysaccharides in wheat grain prevent energy availability and impede the growth performance of boilers. The most prominent non-starch polysaccharide known in wheat is arabinoxylan, which includes almost 10% of this cereal; these particular polymers have a great water-holding capacity of around 10 times their weight. Furthermore, having arabinose in the lateral chain has made it possible for non-starch polysaccharides to become water-soluble. These factors make a high-viscosity condition in the gastrointestinal tract causing a low enzyme-substrate interaction, resulting in weaker digestion and absorption of starch, protein, and fat and, consequently, lower energy retention, which reduces the growth performance of birds. One of the most appropriate methods to improve broiler chickens' performance and decline the negative effects of non-starch polysaccharides (NSPs) in wheat is to apply multi-enzymes. The classic method for enzyme supplementation is to add enzymes over a formulated diet (over the top). Another way for enzyme addition is to consider the nutrient matrix values for the enzyme, which is the most suitable method to decrease the cost of both enzyme and feed consumption. The current study aimed to apply the nutrient matrix values for three different multi-enzymes and evaluate their effects on the performance, water consumption, litter moisture, jejunal viscosity, and some characteristics of the gastrointestinal tract in broilers fed wheat-soybean meal to find an appropriate criterion for the most realistic nutrient matrix values for enzymes. Methods: Three-hundred-day-old male broiler chicks of commercial strain (Ross 308) were studied with four treatments, five replications, and 15 chicks in each replicate in a floor pen. All data were analyzed using a randomized complete design. The four dietary treatments consisted of a wheat-soybean meal-based diet without enzyme (control group) and three wheat-soybean-based diets supplemented with enzymes A, B, and C, which were added at 170, 600, and 500 mg/kg DM, respectively. The nutrient matrix values were considered for enzymes. The effects of treatments on the performance, carcass characteristics, length and weight of intestinal segments, digestive organs weight, water-to-feed intake ratio, and jejunal viscosity were investigated at the end of 42 days. Results: Results of this trial showed that in the starter, finisher, and the whole period, feed intake was not affected by enzyme addition whereas only in the grower period of rearing and only adding enzyme B to the wheat-soybean meal-based diet significantly improved Average Daily Feed Intake (ADFI) (p < 0.05). In the starter period, only the enzyme A addition to a wheat-based diet improved Average Daily Gain (ADG) (p < 0.05). However, in the grower, finisher, and the whole period, ADG was improved by enzyme A and B supplementation (p < 0.05). However, feed conversion ratio (FCR) was not affected by enzyme addition in the starter period (p > 0.05), but using nutrient matrix values for enzymes A and B significantly improved FCR in the grower, finisher, and in the entire period (p < 0.05). Results showed that enzyme supplementation did not significantly affect the relative weight of the pancreas, liver, relative weight and length of the duodenum, jejunum, ileum, and cecum, water to feed intake ratio, and litter moisture (p > 0.05). Birds that received enzyme A and B had lower jejunal content viscosity at day 23 and higher abdominal fat at day 42 (p < 0.05). While carcass yield and thigh relative weight did not change by enzyme supplementation (p > 0.05), breast relative weight for birds that received enzyme A was significantly lower than control treatment and the enzyme C containing group (p < 0.05), and there was no significant difference among enzymes A and B (p > 0.05). Conclusion: The results of the present study showed that the application of nutrient matrix values for enzymes A and B improved the performance of broiler chickens fed a wheat-soybean meal-based diet, and their matrix values could be used for feed formulation to reduce the cost of each kilogram feed. Moreover, the results of the current study showed that using the nutrient matrix value for enzyme C did not significantly affect broiler performance. For assurance, more experiments are needed to be designed to evaluate the nutrient matrix value of this enzyme.